1. Field of the Invention
The present invention relates to an automobile airbag system, and, in particular, to the structure for installing an airbag unit inside an instrument panel of an automobile.
2. Description of Related Art
Typically, passenger-side airbag systems are installed as a supplemental restraint system inside an instrument panel of a vehicle. Such a passenger-side airbag system has an airbag main unit, including an airbag housing, that contains an airbag and an inflator for inflating and expanding the airbag incorporated in the airbag housing. The airbag main unit is closed by an airbag lid attached to the rear opening of the airbag housing. This airbag system is installed inside the instrument panel so that the airbag lid is placed in an opening of the instrument panel and the airbag main unit is attached to and supported by a support member transversely extending inside the instrument panel. Such an airbag system is known from Japanese Unexamined Patent Publication No. 4-59450.
Regarding the structure for installing the airbag system inside the instrument panel, since there is usually some error in relative position between the instrument panel and the support member when the airbag main unit is attached to the support member, the airbag lid may not be correctly positioned in the opening of the instrument panel, e.g., may fail to be uniform or even with the instrument panel. Consequently, the asthetic appearance of the instrument panel including the airbag lid may be spoiled. Conversely, if, after having correctly positioned the airbag lid in the opening of the instrument panel so as to avoid unevenness or discontinuity of the airbag lid with the instrument panel, the attachment of the airbag main unit to the support member may be difficult owing to positional inconsistency between the airbag main unit and the support member.
Further, with such an airbag installation structure, during inflation and expansion of the airbag or when the airbag restrains the passenger, a large energy or external load is sustained by the airbag main unit in the lengthwise direction. This load may damage the fitting members of the airbag main unit to the instrument panel or cause the airbag main unit to shift. Such damages and positional shifts deteriorate the performance of the airbag. For this reason, in order for the airbag system to withstand such a large external load as sustained during expansion and to prevent any deterioration of restraint of the passenger due to damage of the fitting member of the airbag main unit and/or any positional shifting of the airbag main unit, greater support must be provided in a way that can easily be accomplished.